Matched chemistry for HI97719 magnesium hardness testing
Resolve low magnesium hardness in purified-water work with the matched four-component Hanna chemistry. The paired blank-and-sample procedure keeps the reference preparation part of the measurement, while 100- and 300-test packs offer practical replenishment choices for different workloads.
Magnesium reacts with the calmagite indicator to produce a violet color. The method compares differently treated preparations and reports magnesium hardness as calcium carbonate equivalents. “As CaCO₃” is the reporting basis; it is not a direct elemental-magnesium concentration.
Manufacturer reference packaging; printed lot numbers and expiration dates are illustrative, not the dates of supplied stock.
Check the method fit before ordering
HI97719: 0.00–2.00 mg/L as CaCO₃. The HI97719 method is designed for low hardness levels typically found in water-purification systems. It is not a general-purpose magnesium test and is not suitable as a marine or seawater magnesium method.
Prepare the blank and sample correctly
Rinse a graduated beaker with unreacted sample, then fill it to 50 mL. Add 0.5 mL of HI93719A-0, swirl, then add 0.5 mL of HI93719B-0 and swirl again. Rinse two cuvettes with this prepared solution and fill each to 10 mL. Add one drop of HI93719C-0 to cuvette 1 (the blank) and one drop of HI93719D-0 to cuvette 2 (the sample); stopper, cap and invert each several times. Zero the HI97719 with cuvette 1, then read cuvette 2.
Keep cuvettes clean and dry on the outside, free of fingerprints and bubbles. Fit stoppers and caps securely and follow the manual’s cuvette orientation and handling guidance. This overview does not replace the complete instrument method.
Sample limits that matter
Excessive heavy metals can interfere. When dilution is required, use hardness-free water: ordinary water introduces its own hardness and biases the result. The manual describes a 100-fold preparation using 0.5 mL of sample made up to 50 mL; apply the appropriate dilution factor and follow the full method. Do not use dilution alone as proof that a marine or otherwise unvalidated matrix is suitable.
What the reagent pack includes
The selected pack supplies liquid reagents A, B, C and D for 100 or 300 magnesium-hardness tests. The photometer, two cuvettes with stoppers and caps, graduated beaker, measuring accessories, hardness-free dilution water and CAL Check standards are separate. Have the method’s required accessories available before starting.
Choose 100 or 300 tests
HI93719-01 provides 100 tests; HI93719-03 provides 300 tests. Both use the same method chemistry and measurement range. Select the smaller pack for lower-volume testing or the larger pack for more frequent sampling, considering your likely use before the marked expiry. Test counts describe analytical capacity, not a promise of a particular shipping-box bottle or packet arrangement.
Documented instrument support
Exact-model manuals in the reagent map list both pack sizes for HI97719, HI97736, HI97741, HI97745, HI83300, HI83399. Follow the procedure and reporting basis for your own instrument. The range and workflow above refer specifically to HI97719.
Hanna’s US retail title says “Magnesium and Total Hardness Reagents.” On HI97719, these reagents measure magnesium hardness only; that title does not add a total-hardness mode to this meter. This is not HI937520 chemistry for HI97752 general magnesium testing.
Handle the chemistry, not just the result
Review the linked US Safety Data Sheets for all four liquid components before use. Hanna classifies these HI93719 packs as Dangerous Goods for ground shipment only. Follow the SDS and laboratory procedures for personal protection, storage and waste disposal. Check the supplied reagent labels before every run.
Frequently Asked Questions
Which pack should I select?
HI93719-01 supplies 100 tests and HI93719-03 supplies 300 tests. Both are the same reagent family; the larger test count does not extend the range. Match expected use to the marked shelf life.
What does the HI97719 result mean?
The range is 0.00–2.00 mg/L as CaCO₃. This is magnesium hardness expressed as calcium carbonate equivalents, not mg/L Mg²⁺. The HI97719 can also display French degrees (°f), German degrees (°dH) or English degrees (°E).
Which reagent components are used?
The method uses HI93719A-0 and HI93719B-0 at 0.5 mL each in a 50 mL sample preparation. One drop of HI93719C-0 goes into the blank cuvette and one drop of HI93719D-0 into the sample cuvette.
Why are two cuvettes needed?
The HI97719 compares a blank treated with reagent C against a sample treated with reagent D. Prepare both from the same A/B-treated solution, zero with the blank, then read the sample. They are not duplicate readings of an untreated water sample.
Can I use it for seawater magnesium?
No. This low-range magnesium-hardness chemistry is not a marine/seawater magnesium method. It is not interchangeable with HI97752 / HI937520 elemental-magnesium chemistry, and the HI97719 does not gain a total-hardness mode from the retail pack name.
What should I use for dilution?
Excessive heavy metals can interfere. When dilution is required, use hardness-free water: ordinary water introduces its own hardness and biases the result. The manual describes a 100-fold preparation using 0.5 mL of sample made up to 50 mL; apply the appropriate dilution factor and follow the full method. Do not use dilution alone as proof that a marine or otherwise unvalidated matrix is suitable.
Are the meter and accessories supplied?
The selected pack supplies liquid reagents A, B, C and D for 100 or 300 magnesium-hardness tests. The photometer, two cuvettes with stoppers and caps, graduated beaker, measuring accessories, hardness-free dilution water and CAL Check standards are separate. Have the method’s required accessories available before starting.
What handling and storage information should I follow?
Use the current linked US SDS documents for A, B, C and D and the supplied labels for storage, protective equipment and disposal. Each bottle has lot and expiration traceability. These packs are Dangerous Goods for ground shipment only.
